Oil mists from machining operations have long been associated with occupational disease in exposed workers. Concern has increased with recent evidence that exposure to these mists is associated with throat, pancreas, rectum, and prostate cancers as well as breathing problems and respiratory illnesses. As a result, the ACGIH has published a notice of intent to change the TLV for mists of "mildly refined oils" from 5 to 0.2 mg/m3. Thus, accurate methods to,monitor the personal exposure of workers to these mists is important. Unfortunately, mineral oils used in machining operations contain semi-volatile compounds that, during sampling itself, can evaporate from the filter used to monitor mist concentration using the NIOSH standard method. To the extent that evaporation occurs, such measurements will underestimate workers' true exposures. This proposal is to develop a personal monitor for oil mists that is less susceptible to evaporation of semi-volatile compounds. Recent advances in electronics make possible a personal electrostatic monitor that collects oil mists in a way that minimizes the potential for evaporation, and so allows assessment of workers' true exposures. In the work proposed here, such a monitor will be developed and evaluated through laboratory and field trials.